rum B. Rosen Internet-Draft 14 June 2021 Intended status: Standards Track Expires: 16 December 2021 Interoperability Profile for Relay User Equipment draft-ietf-rum-rue-05 Abstract Video Relay Service (VRS) is a term used to describe a method by which a hearing persons can communicate with deaf/Hard of Hearing user using an interpreter ("Communications Assistant") connected via a videophone to the deaf/HoH user and an audio telephone call to the hearing user. The CA interprets using sign language on the videophone link and voice on the telephone link. Often the interpreters may be supplied by a company or agency termed a "provider" in this document. The provider also provides a video service that allows users to connect video devices to their service, and subsequently to CAs and other deaf/HoH users. It is desirable that the videophones used by the deaf/HoH/H-I user conform to a standard so that any device may be used with any provider and that video calls direct between deaf/HoH users work. This document describes the interface between a videophone and a provider. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 16 December 2021. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. Rosen Expires 16 December 2021 [Page 1] Internet-Draft Relay User Equipment Profile June 2021 This document is subject to BCP 78 and the IETF Trust’s Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . 3 2. Terminology . 3 3. Requirements Language . 5 4. General Requirements . 6 5. SIP Signaling . 6 5.1. Registration . 7 5.2. Session Establishment . 8 5.2.1. Normal Call Origination . 8 5.2.2. One-Stage Dial-Around Origination . 9 5.2.3. RUE Contact Information . 10 5.2.4. Incoming Calls . 10 5.2.5. Emergency Calls . 11 5.3. Mid Call Signaling . 11 5.4. URI Representation of Phone Numbers . 12 5.5. Transport . 12 6. Media . 12 6.1. SRTP and SRTCP . 13 6.2. Text-Based Communication . 13 6.3. Video . 13 6.4. Audio . 13 6.5. DTMF Digits . 13 6.6. Session Description Protocol . 13 6.7. Privacy . 14 6.8. Negative Acknowledgment, Packet Loss Indicator, and Full Intraframe Request Features . 14 7. Contacts . 14 7.1. CardDAV Login and Synchronization . 14 7.2. Contacts Import/Export Service . 15 8. Mail Waiting Indicator (MWI) . 15 9. Provisioning and Provider Selection . 15 9.1. RUE Provider Selection . 15 9.2. RUE Configuration Service . 17 9.3. Using the Provider List and Configuration Services Together . 21 9.4. OpenAPI Interface Descriptions . 21 10. Acknowledgements . 26 11. IANA Considerations . 26 Rosen Expires 16 December 2021 [Page 2] Internet-Draft Relay User Equipment Profile June 2021 11.1. RUE Provider List Registry . 27 11.2. Registration of rue-owner purpose parameter . 27 12. Security Considerations . 27 13. Normative References . 27 Author’s Address . 33 1. Introduction Video Relay Service (VRS) is a form of Telecommunications Relay Service (TRS) that enables persons with hearing disabilities who use sign language, such as American Sign Language (ASL), to communicate with voice telephone users through video equipment. These services also enable communication between such individuals directly in suitable modalities, including any combination of sign language via video, real-time text (RTT), and speech. This Interoperability Profile for Relay User Equipment (RUE) is a profile of the Session Initiation Protocol (SIP) and related media protocols that enables end-user equipment registration and calling for VRS calls. It specifies the minimal set of call flows, Internet Engineering Task Force (IETF) and ITU-T standards that must be supported, provides guidance where the standards leave multiple implementation options, and specifies minimal and extended capabilities for RUE calls. Both deaf/HoH to provider (interpreted) and direct deaf/HoH to deaf/ HoH calls are supported on this interface. While there are some accommodations in this document to maximize backwards compatibility with devices and services that conform to this document, backwards compatibility is not a requirement, and some interwork may be required to allow direct video calls to older devices. This document only describes the interface between the device and the provider, and not any other interface the provider may have. 2. Terminology Communication Assistant (CA): A sign-language interpreter working for a VRS Provider, providing functionally equivalent phone service. Communication modality (modality): A specific form of communication that may be employed by two users, e.g., English voice, Spanish voice, American Sign Language, English lip-reading, or French real- time-text. Here, one communication modality is assumed to encompass both the language and the way that language is exchanged. For example, English voice and French voice are two different communication modalities. Rosen Expires 16 December 2021 [Page 3] Internet-Draft Relay User Equipment Profile June 2021 Default video relay service: The video relay service operated by a subscriber’s default VRS provider. Default video relay service Provider (Default Provider): The VRS provider that registers, and assigns a telephone number to a specific subscriber, and by default provides the VRS for incoming voice calls to the user. The default Provider also by default provides VRS for outgoing relay calls. The user can have more than one telephone number and each has a default provider. Dial-around call: A relay call where the subscriber specifies the use of a VRS provider other than the default VRS provider. This can be accomplished by the user dialing a "front-door" number for a VRS provider and signing or texting a phone number to call ("two-stage"). Alternatively, this can be accomplished by the user’s RUE software instructing the server of its default VRS provider to automatically route the call through the alternate Provider to the desired public switched telephone network (PSTN) directory number ("one-stage"). Dial-around is per-call -- for any call, a user can use the default VRS provider or any dial-around VRS provider. Full Intra Request (FIR): A request to a video media sender, requiring that media sender to send a Decoder Refresh Point at the earliest opportunity. FIR is sometimes known as "instantaneous decoder refresh request", "video fast update request", or "fast update request". Point-to-Point Call (P2P Call): A call between two RUEs, without including a CA. Relay call: A call that allows persons with hearing or speech disabilities to use a RUE to talk to users of traditional voice services with the aid of a communication assistant (CA) to relay the communication. Please refer to FCC-VRS-GUIDE. Relay-to-relay call: A call between two subscribers each using different forms of relay (video relay, IP relay, TTY), each with a separate CA to assist in relaying the conversation. Relay service (RS): A service that allow a registered subscriber to use a RUE to make and receive relay calls, point-to-point calls, and relay-to-relay calls. The functions provided by the relay service include the provision of media links supporting the communication modalities used by the caller and callee, and user registration and validation, authentication, authorization, automatic call distributor (ACD) platform functions, routing (including emergency call routing), call setup, mapping, call features (such as call forwarding and video mail), and assignment of CAs to relay calls. Rosen Expires 16 December 2021 [Page 4] Internet-Draft Relay User Equipment Profile June 2021 Relay service Provider (Provider): An organization that operates a relay service. A subscriber selects a relay service Provider to assign and register a telephone number for their use, to register with for receipt of incoming calls, and to provide the default service for outgoing calls. Relay user: Please refer to "subscriber". Relay user E.164 Number (user E.164): The telephone number (in ITU-T E.164 format) assigned to the user. Relay user equipment (RUE): A SIP user agent (UA) enhanced with extra features to support a subscriber in requesting and using relay calls. A RUE may take many forms, including a stand-alone device; an application running on a general-purpose computing device such as a laptop, tablet or smart phone; or proprietary equipment connected to a server that provides the RUE interface. RUE Interface: the interfaces described in this document between a RUE and a VRS provider who supports it Sign language: A language that uses hand gestures and body language to convey meaning including, but not limited to, American Sign Language (ASL). Subscriber: An individual who has registered with a Provider and who obtains service by using relay user equipment. This is the traditional telecom term for an end-user customer, which in our case is a relay user.